Hydrolysis surfactant effects

Eriksson, T., Borjesson, J., and Tjerneld, F. 2002. Mechanism of surfactant effect in enzymatic hydrolysis of lignocellulose. Enz. Microbial Technol., 31, 353-364. 

Tsai, S.W., Lee, K.P., Chiang, C.L. 1995. Surfactant effects on lipase catalyzed hydrolysis of olive oil in AOT/isooctane reverse micelles. Biocatal. Biotrans. 13, 89-98. 

Ebrahimi, S., et al., 2005. Biofibn growth pattern in honeycomb monoUth packings effect of shear rate and substrate transport Umitations. Catalysis Today 105 (3—4), 448—454. Eriksson, T., Botjesson, J., Tjemeld, F., 2002. Mechanism of surfactant effect in enzymatic hydrolysis of UgnoceUulose. Enz3me and Microbial Technology 31 (3), 353—364. 

Inspired by the many hydrolytically-active metallo enzymes encountered in nature, extensive studies have been performed on so-called metallo micelles. These investigations usually focus on mixed micelles of a common surfactant together with a special chelating surfactant that exhibits a high affinity for transition-metal ions. These aggregates can have remarkable catalytic effects on the hydrolysis of activated carboxylic acid esters, phosphate esters and amides. In these reactions the exact role of the metal ion is not clear and may vary from one system to another. However, there are strong indications that the major function of the metal ion is the coordination of hydroxide anion in the Stem region of the micelle where it is in the proximity of the micelle-bound substrate. The first report of catalysis of a hydrolysis reaction by me tall omi cell es stems from 1978. In the years that... 

Amidosulfonates. Amidosulfonates or A/-acyl-A/-alkyltaurates, are derived from taurine, H2NCH2CH2S02Na, and are effective surfactants and lime soap dispersants (Table 9). Because of high raw material cost, usage is relatively small. Technically, amidosulfonates are of interest because they are stable to hydrolysis, unaffected by hard water, and compatible with soap. They have been used in soap—surfactant toilet-bar formulations. With shorter, acyl groups, they make excellent wetting agents. 

Hydrolysis of 2-perfluoroalkylethyl iodides in the presence of nitrites also gives 2-perfluoroalkylethanols [5/] (equation 51). A variety of solvents can be used, but acetonitrile appears the most effective. Solvents can be avoided by using a betaine surfactant as a phase-transfer catalyst. 

Similarly to quantitative determination of high surfactant concentrations, many alternative methods have been proposed for the quantitative determination of low surfactant concentrations. Tsuji et al. [270] developed a potentio-metric method for the microdetermination of anionic surfactants that was applied to the analysis of 5-100 ppm of sodium dodecyl sulfate and 1-10 ppm of sodium dodecyl ether (2.9 EO) sulfate. This method is based on the inhibitory effect of anionic surfactants on the enzyme system cholinesterase-butyryl-thiocholine iodide. A constant current is applied across two platinum plate electrodes immersed in a solution containing butyrylthiocholine and surfactant. Since cholinesterase produces enzymatic hydrolysis of the substrate, the decrease in the initial velocity of the hydrolysis caused by the surfactant corresponds to its concentration. Amounts up to 60 pg of alcohol sulfate can be spectrometrically determined with acridine orange by extraction of the ion pair with a mixture 3 1 (v/v) of benzene/methyl isobutyl ketone [271]. 

The catalytic activity of surfactant micelles and the effect of the concentration of reagents in micelle catalysis are tested on hydrolysis of esters of phosphorus acids [25],... 

Nanoparticles of the semicondnctor titanium dioxide have also been spread as mono-layers [164]. Nanoparticles of TiOi were formed by the arrested hydrolysis of titanium iso-propoxide. A very small amount of water was mixed with a chloroform/isopropanol solution of titanium isopropoxide with the surfactant hexadecyltrimethylammonium bromide (CTAB) and a catalyst. The particles produced were 1.8-2.2 nm in diameter. The stabilized particles were spread as monolayers. Successive cycles of II-A isotherms exhibited smaller areas for the initial pressnre rise, attributed to dissolution of excess surfactant into the subphase. And BAM observation showed the solid state of the films at 50 mN m was featureless and bright collapse then appeared as a series of stripes across the image. The area per particle determined from the isotherms decreased when sols were subjected to a heat treatment prior to spreading. This effect was believed to arise from a modification to the particle surface that made surfactant adsorption less favorable. 

The effect of mixtures of surfactants and polyelectrolytes on spontaneous, water-catalysed hydrolysis (Fadnavis and Engberts, 1982) was mentioned in Section 4, but mixtures of functionalized polyelectrolytes and cationic surfacants are effective deacylating agents (Visser et al., 1983). Polymerized isocyanides were functionalized with an imidazole group and the deacylation of 2,4-dinitrophenyl acetate in the polyelectrolyte was speeded by addition of single or twin chain quaternary ammonium ion surfactants, up to a plateau value. Anionic surfactants had essentially no effect. It is probable that the cationic surfactants accelerate the reaction by increasing the deprotonation of the imidazole groups. 

N-Alkylhydroxamic acid hydrolysis Methyl Violet + OH" Cl C12H25S03Na + H30+, CTABr + OH". An attempt made to separate electronic and hydrophobic effects on the micellar reaction Anionic and cationic micelles. Effect of surfactant structure examined Berndt el at., 1984 Malaviya and Katiyar, 1984... 

HS may alter the reactivities of bound substrates in a way similar to that of anionic surfactants (inhibiting base-catalyzed and accelerating acid-catalyzed reactions). These effects were attributed to electrostatic stabilization of the transition state for the acid catalysis in which the substrate becomes more positively charged, and to destabilization of the transition state for base-catalyzed hydrolysis in which the substrate becomes more negatively charged. 

Kandori, K Hori, I. Yasukawa, A. Ishikawa, T. (1995) Effects of surfactants on the precipitation and properties of colloidal particles from forced hydrolysis of EeCl3-HCl solution. J. Mat. Sci. 30 2145-2152 Kandori, K Kawashima,Y. Ishikawa, T. 

The effect of the local non-neutral environment (4) should be considered together with the detailed reaction mechanism of the hydrolysis reaction and together with the charge development in the activation process in particular. The electrostatically non-neutral environment offered by ionic micelles is generally thought to be the reason for the observation that rate-retarding effects exerted by anionic surfactants on this type of hydrolysis reaction are typically stronger than those by other surfactants. 

For a surface active betaine ester the rate of alkaline hydrolysis shows significant concentration dependence. Due to a locally elevated concentration of hydroxyl ions at the cationic micellar surface, i.e., a locally increased pH in the micellar pseudophase, the reaction rate can be substantially higher when the substance is present at a concentration above the critical micelle concentration compared to the rate observed for a unimeric surfactant or a non-surface active betaine ester under the same conditions. This behavior, which is illustrated in Fig. 10, is an example of micellar catalysis. The decrease in reaction rate observed at higher concentrations for the C12-C18 1 compounds is a consequence of competition between the reactive hydroxyl ions and the inert surfactant counterions at the micellar surface. This effect is in line with the essential features of the pseudophase ion-exchange model of micellar catalysis [29,31]. 

The alcohol formed on hydrolysis of a betaine ester surfactant has strong effects on the shape of its aggregates and its phase behavior. In a micellar solution of dodecyl betainate, addition of 10 to 20% of dodecanol causes a significant aggregate growth (higher additions cause phase separation) [29]. In... 

The effects of dilution of the micellar surface charge on the rate of alkaline hydrolysis of a betaine ester surfactant have been investigated for a mixture of decyl betainate and a nonionic surfactant with a similar CMC. It was shown that the relation between micellar composition and the hydrolysis rate essentially parallels the relation between micellar composition and counterion binding to mixed micelles made up of ionic and nonionic surfactants [20]. 

Hydrolysis of acetals yields aldehydes, which are intermediates in the biochemical /3-oxidation of hydrocarbon chains. Acid catalyzed hydrolysis of unsubstituted acetals is generally facile and occurs at a reasonable rate at pH 4-5 at room temperature. Electron-withdrawing substituents, such as hydroxyl, ether oxygen, and halogens, reduce the hydrolysis rate, however [50]. Anionic acetal surfactants are more labile than cationic [40], a fact that can be ascribed to the locally high oxonium ion activity around such micelles. The same effect can also be seen for surfactants forming vesicular aggregates. 

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